海南岛热带土壤无机磷的形态和性质

土壤无机磷的形态、含量和分布是土壤形成过程表现出来的一种化学性质。海南岛热带土壤无机磷的形态分级的研究结果表明。(1) 海南岛早地土壤无机磷总量受到成土母质的深刻影响。玄武岩砖红壤无机磷总量>变质岩(云母片岩)和砂页岩砖红壤>红色石灰土>花岗岩砖红壤>浅海沉积物砖红壤和燥红土。(2) 土壤发育程度对闭蓄态磷(O—P)和非闭蓄态磷(非O—P)的相对比例的影响超过母质的作用,但非O—P的形态组成却与母质关系密切。玄武岩、砂页岩发育的土壤以磷酸铁盐(Fe—P)为主;花岗岩和浅海沉积物发育的土壤,磷酸钙盐(Ca—P)和磷酸铝盐(Al—P)相对含量较高。(3) 一般来说,土壤表层的无机磷总量、非O—P和有效磷都高于心土层,而表层O—P含量则低于下层。发育程度高的砖红壤无机磷在剖面上的分布比幼年土均匀。(4) 海南岛各类土壤有效磷水平差异很大,其高低主要决定土壤的发育程度和土壤无机磷的形态组成。

FORMS AND PROPERTIES OF INORGANIC PHOSPHORUS IN TROPICAL SOILS ON HAINAN ISLAND

Studies were conducted on the fractionation of inorganic phosphoric forms in the main soil types of Hainan Island. The results obtained are as follows: (1) The total inorganic phosphorus in different soils of Hainan Island was significantly conditioned by their parent rocks in the following order: basalt latosoE>metamorphic(micaschist)and sandstone latosol>limestone red loam>granite latosol>shallow-sea deposit latosol and dry red earth. (2) As compared with parent rocks, development of soils brought about greater effect on the relative ratio between occluded phosphorus (O-P) and non-occluded phosphorus(non O-P). However, the formal constitution of non O-P was closely correlated with parent rocks. Fe-phosphates(Fe-P)were the main contents of non O-P in the soil developed from basalt and metamorphic rocks, but the relative conents of Ca-phosphates (Ca-P)and Al-phosphates (Al-P) in the soils developed from granite and shallow-sea deposit were higher. (3) In general, the contents of total inorganic phosphorus, non O-P and available P were higher in the surface soil than in the subsoil, but the content of O-P was lower in the former soil than in the latter. The distribution of inorganic phosphorus on the profiles was more even in better developed latosol than in young latosols. (4) The content of available P in the tropical soils of Hainan Island varied widely with the development and the forms of inorganic phosphorus in the soils.